Air displacement pipetters with disposable tips have been used in the medical industry for many years. The main reason for such continual acceptance comes from the fact that after each use the tip has traditionally been disposed of, thereby limiting the possibility of cross contamination between samples. However, because of the need to perform many tests from a limited account of sample quantity, polymerase chain reaction (PCR) was developed. PCR (covered under U.S. patents issued to CETUS Corporation), provides a method with which to produce many copies of a specific nucleotide sequence from a minute quantity of DNA.
Unfortunately, false signals can be generated following PCR amplification due to cross-contamination accuracy during carry-over between existing tips and air displacement pipetters. As the scrutinizing of these and many more tests have become more demanding, the need to eliminate any and all cross contamination is imperative. Even the smallest amounts of particles left behind on the barrel of the pipetter from previous tests can invalidate, or skew the evaluations of new test samples, causing hours or even days of laboratory research to be wasted. These errors could be contributed to operator use (which often causes splashing of the sample) or the sample could aerosol during aspiration of the fluid sample, or the fluids contaminated gases can flow into the tip upward into the calibrated barrel in the form of air borne contaminates.
The filtered disposable pipette tip was developed to help prevent such problems. However as shown below, the advantages of the existing designs do not meet the more stringent requirements for test evaluations of today's medical requirements.